ORA-12537: TNS: connection closed

discover problems There are too many connections in the test environment. It is found that all the links are in the second rac node. No one calls or cares about the test environment Manually test the specified instance: C:\Users\caoyf>sqlplus system/xxxx@192.168.xxx.xxx:1521/server_taf SQL*Plus: Release 11.2.0.4.0 Producti ...

Posted by V on Tue, 26 Nov 2019 18:36:24 +0100

001. Analysis of operation principle of JAVA program

1. First look at the structure of the JVM runtime data area Thread exclusive: Each thread has its own space that is created and destroyed with the thread lifecycle. Thread sharing: All threads have access to this memory data, which is created and destroyed with the virtual machine GC. JVM stores loaded class information, constants, static var ...

Posted by shawngoldw on Thu, 21 Nov 2019 19:38:35 +0100

java links Oracle(JDBC)

Tools: eclipse jdk 1.8 oracle 11g ojdbc6.jar(Database driver package) Six steps of JDBC: Here we follow these six steps of jdbc: Registration driven Get connection Get execution sql statement object Execute sql statement Process result set close resource URL: Uniform Resource Locator oracle URL: jdbc:orac ...

Posted by bobbfwed on Fri, 08 Nov 2019 16:05:50 +0100

springboot2.1.5 + mybatis to configure multiple data sources

1. Startup is the way to create bean s pom.xml <dependency> <groupId>com.alibaba</groupId> <artifactId>druid-spring-boot-starter</artifactId> <version>1.1.10</version> </dependency> <!-- maven Not in the warehouse oracle Database driver, here jar Put it under the project for i ...

Posted by partypete on Mon, 04 Nov 2019 16:37:20 +0100

Application of Radiology principle to realize cross database operation (obtaining member information in assembly by reflection)

1. The concept of reflection has been explained in the blog in the previous section. Next, we start to analyze the business requirements logic, and then use the reflection principle to realize it;2. Description: Usually, only one database can be connected to operate data in a project, but some complex businesses will u ...

Posted by joey3002 on Mon, 04 Nov 2019 00:01:49 +0100

Talk about bootstrappcheck of Elasticsearch

order This paper mainly studies bootstrap check of elastic search BootstrapCheck elasticsearch-7.0.1/server/src/main/java/org/elasticsearch/bootstrap/BootstrapCheck.java public interface BootstrapCheck { /** * Encapsulate the result of a bootstrap check. */ final class BootstrapCheckResult { private final String mess ...

Posted by paschim on Sun, 03 Nov 2019 18:11:36 +0100

Judgment of field value null and '' null in different databases and SpringDataJPA

Reason: when using the spring datajpa statement to query the null value of a field in the database table, such as:findByIdAndNameIsNullfindByIdAndNameIsNotNullWhen the value of name is empty string, the result of query is very different 1. Build tables CREATE TABLE `user` ( `id` bigint(11) NOT NULL AUTO_INCREMENT, `name` varchar(45) CHARAC ...

Posted by Teen0724 on Sun, 03 Nov 2019 02:42:33 +0100

Unique identification of order

When designing a table structure in a normal development system, it is often necessary to have a field to identify the uniqueness of the record, which is implemented from different dimensions of the java level and the database level java generates unique identity Version 1 Unique identifier UUID generated by java System.out.println(UUID.rando ...

Posted by winggundamth on Sat, 02 Nov 2019 21:16:48 +0100

Quick Oracle server script installation on CentOS

  Configure repos source # cd /etc/yum.repos.d # wget http://yum.oracle.com/public-yum-ol7.repo The official website points out that the version to be installed is enable =1, so you need to modify the. repo file.   Download RMP-GPG-KEY wget http://public-yum.oracle.com/RPM-GPG-KEY-oracle-ol7 -O /etc/pki/rpm-gpg ...

Posted by John_wilson on Sat, 02 Nov 2019 00:44:25 +0100

Encapsulating query, adding, deleting, modifying and connecting database

encapsulation BaseDao What if the parameter, quantity and type are not fixed? public class TestMethod { //First, method overload /*public int sum(int a) { return a; } public int sum(int a,int b) { return a+b; } public int sum(int a,int b,int c) { return a+b+c; }*/ //Method 2, put an arra ...

Posted by anand on Sun, 20 Oct 2019 16:43:04 +0200